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Xii                                  JPI-ATAXriSTA AND INI A                              381
The following are its main characters :—Dorsal fin absent. Eyes
rudimentary. Pectoral fins large and truncated at the extremity.
Teeth, about twenty-nine in each half of each jaw. Scapula with
the acroniion coinciding with its anterior edge. Skull with enormous
maxillary crests, and with the palatines entirely concealed by the
pterygoids. The length of the above definition will serve to
indicate how anomalous in many particulars is the structure of
this " Dolphin/'
There is apparently but one species, P. gnngetica^ the " Susu."
The Indian vernacular name is derived from the sound that the
animal makes when spouting. It is an inhabitant of the Ganges
and the Indus, together with their tributaries, and ascends very
high up its streams. It is also thought to "be purely fluviatile
and never to desert the rivers for the sea. JPlatanista lives
chiefly by grubbing: in the mud for prawns and fish. Grains
of rice have also been found in the stomach, but this would seem
to be accidental. The long snout of the Susu has been compared
to tli-2 long snout of the G-harial, a native of the same region.
This Whale grows \o a length of over 9 feet, but this length is
exceptional. Its anatomy has been elaborately described by Dr.
The next genus, Inia, is thus to be characterised :—Dorsal fin
rudimentary ; pectorals large and ovate. Teeth, as many as thirty-
two on each side, often with an additional tubercle. Skull without
large maxillary crests; palatines not hidden by pterygoids^ but
divided by vomer. The vertebrae of this genus are few in
number, only forty-one in all, which are thus distributed : C 7,
D 13, I* 3, Ca 18. The peculiarities of the vertebral column
are several. In the first place, as has been mentioned in the
definition of the family, all the cervicals are separate and
individually of some length. Secondly 9 the axis has a better
trace of an odontoid process than, in any other Whale except
Platanista, where it is even more obvious. The lumbar region is
remarkable on account of its restriction to three vertebrae. The
sternum, by what we must regard as convergence, is somewhat
like that of the Whalebone whales. It consists of one piece only,
of a roughly-oval form, to which apparently only two pairs of
(cartilaginous) sternal ribs are attached. In the fore-limb the
proportions between the humerus and the radius are more like
1 Anatomical Jtesearchese JVwnati Mep. 1878, p. 417.